+
+ reset_decoded_audio ();
+}
+
+void
+AudioDecoder::reset_decoded_audio ()
+{
+ _decoded_audio = ContentAudio (shared_ptr<AudioBuffers> (new AudioBuffers (_audio_content->audio_channels(), 0)), 0);
+}
+
+shared_ptr<ContentAudio>
+AudioDecoder::get_audio (AudioFrame frame, AudioFrame length, bool accurate)
+{
+ shared_ptr<ContentAudio> dec;
+
+ AudioFrame const end = frame + length - 1;
+
+ if (frame < _decoded_audio.frame || end > (_decoded_audio.frame + length * 4)) {
+ /* Either we have no decoded data, or what we do have is a long way from what we want: seek */
+ seek (ContentTime::from_frames (frame, _audio_content->audio_frame_rate()), accurate);
+ }
+
+ /* Offset of the data that we want from the start of _decoded_audio.audio
+ (to be set up shortly)
+ */
+ AudioFrame decoded_offset = 0;
+
+ /* Now enough pass() calls will either:
+ * (a) give us what we want, or
+ * (b) hit the end of the decoder.
+ *
+ * If we are being accurate, we want the right frames,
+ * otherwise any frames will do.
+ */
+ if (accurate) {
+ /* Keep stuffing data into _decoded_audio until we have enough data, or the subclass does not want to give us any more */
+ while (!pass() && (_decoded_audio.frame > frame || (_decoded_audio.frame + _decoded_audio.audio->frames()) < end)) {}
+ decoded_offset = frame - _decoded_audio.frame;
+ } else {
+ while (!pass() && _decoded_audio.audio->frames() < length) {}
+ /* Use decoded_offset of 0, as we don't really care what frames we return */
+ }
+
+ /* The amount of data available in _decoded_audio.audio starting from `frame'. This could be -ve
+ if pass() returned true before we got enough data.
+ */
+ AudioFrame const available = _decoded_audio.audio->frames() - decoded_offset;
+
+ /* We will return either that, or the requested amount, whichever is smaller */
+ AudioFrame const to_return = max ((AudioFrame) 0, min (available, length));
+
+ /* Copy our data to the output */
+ shared_ptr<AudioBuffers> out (new AudioBuffers (_decoded_audio.audio->channels(), to_return));
+ out->copy_from (_decoded_audio.audio.get(), to_return, decoded_offset, 0);
+
+ AudioFrame const remaining = max ((AudioFrame) 0, available - to_return);
+
+ /* Clean up decoded; first, move the data after what we just returned to the start of the buffer */
+ _decoded_audio.audio->move (decoded_offset + to_return, 0, remaining);
+ /* And set up the number of frames we have left */
+ _decoded_audio.audio->set_frames (remaining);
+ /* Also bump where those frames are in terms of the content */
+ _decoded_audio.frame += decoded_offset + to_return;
+
+ return shared_ptr<ContentAudio> (new ContentAudio (out, frame));